<#--
 * 递归调用，树形结构
 * 范例   <@buildNode child=data.treeRoot.child parent=data.treeRoot/>
 -->
<#macro buildNode child parent> 
    <#if child?? && child?size gt 0> 
        <#list child as t> 
            //to build tree node 
            <@buildNode child=t.child parent=t/> 
        </#list> 
    </#if> 
</#macro>